Heterocyclyl anthracyclinone derivatives

ABSTRACT

A compound of formula (1) wherein R 1  is hydrogen, hydroxy, a group of formula OR 5  wherein R 5  is C 1 -C 6  alkyl, C 2 -C 6  alkenyl or C 3 -C 8  cycloalkyl, halogen, amino which may be unsubstituted or mono or disubstituted by C 1 -C 6  alkyl, C 2 -C 6  alkenyl, aralkyl, acyl or trifluoroacetyl; R 2  is hydrogen, hydroxy, a group NR 6 R 7  wherein R 6  and R 7  independently represent hydrogen, an optionally substituted C 1 -C 6  alkyl, C 2 -C 6  alkenyl, C 3 -C 8  cycloalkyl or, taken together with the nitrogen atom, represent an optionally substituted C 3 -C 8  heterocyclic ring; R 3  is hydrogen, hydroxy, R 4  is a 2-substituted thiazolyl or imidazolyl system and the pharmaceutically acceptable salt thereof, is useful in the treatment of amyloidosis. Processes for the preparation and pharmaceutical compositions are also described.

This application is a National Stage of International ApplicationPCT/EP99/01554, filed Mar. 4, 1999, which claims priority to GB9805082.6, filed Mar. 10, 1998.

The present invention relates to 9-heterocyclyl anthracyclinonederivatives, to their use for the treatment of amyloidoses, to methodsfor their preparation and to pharmaceutical compositions containingthem. More particularly, the present invention provides anthracyclinonederivatives which are characterized by the presence of a penta-atomicheterocyclic system linked to the position 9 of the anthracyclinonesystem and that are represented by the general formula 1

wherein:

R₁ is selected from:

hydrogen,

hydroxy,

a group of formula OR₅ wherein R₅ is C₁-C₆ alkyl, C₂-C₆ alkenyl or C₃-C₈cycloalkyl,

halogen,

and amino which may be unsubstituted or mono or disubstituted by C₁-C₆alkyl, C₂-C₆ alkenyl, aralkyl, acyl or trifluoroacetyl;

R₂ is selected from:

hydrogen,

hydroxy, and

a group NR₆R₇ wherein R₆ and R₇ independently represent hydrogen, anoptionally substituted C₁-C₆ alkyl, C₂-C₆ alkenyl, C₃-C₈ cycloalkyl or,taken together with the nitrogen atom, represent an optionallysubstituted C₃-C₈ heterocyclic ring;

R₃ is selected from:

hydrogen and

hydroxy;

R₄ is a 2-substituted thiazolyl or imidazolyl system of formula A:

wherein z represents sulfur or nitrogen and R₆ and R₇ are as definedabove, and the pharmaceutically acceptable salt thereof.

The term “alkyl” as used herein includes both straight and branchedchain radicals of up to 6 carbons, for example methyl, ethyl, propyl,butyl, pentyl, hexyl and the various branched chain isomers thereof, aswell as straight and branched chain radicals optionally carrying one ormore substituents selected from aryl, cycloalkyl, halogen,trifluoromethyl, hydroxy, alkoxy, aralkoxyl, amino, mono ordialkylamino, carboxy.

The term “alkenyl” as used herein includes both straight and branchedchain radicals of up to 6 carbons such as, for example, allyl, butenyl,pentenyl, hexenyl, optionally subsituted as the alkyl groups above.

The term “cycloalkyl” as used herein means a cycloalkyl group having 3to 8 carbons, for example cyclopropyl, cyclobutl, cyclopentyl,cyclohexyl, cycloheptyl and cyclooctyl, optionally subsituted as thealkyl groups above. The term “aryl” as used herein includes bothmonocyclic or bicyclic aromatic groups containing from 6 to 10 carbonsin the ring portion such as phenyl or naphthyl, optionally substitutedby one or more substituents selected from C₁-C₆ alkyl, C₁-C₆ alkoxyl,trifluoromethyl, halogen or hydroxy. The term “heterocyclyl” as usedherein is a 3- to 7-membered, saturated or unsaturated heterocyclic ringcontaining at least one heteroatom selected from N, O and S and which isoptionally fused to a second 5- or 6-membered, saturated or unsaturatedheterocyclic ring or to an aryl ring, optionally substituted by one ormore substituents selected from C₁-C₆ alkyl, C₁-C₆ alkoxyl,trifluoromethyl, halogen or hydroxy.

The term “halogen” as used herein means fluorine, chlorine, bromine andiodine.

The term “aralkyl” as used herein refers to alkyl groups as previouslydefined having an aryl substituent, for example benzyl, phenethyl,diphenylmethyl and triphenylmethyl.

The term “alkoxyl” or “aralkoxyl” as used herein includes any of theabove alkyl, cycloalkyl or aralkyl groups linked to an oxygen atom.

The term “acyl” as employed herein includes alkyl, aryl and heterocyclylas described above linked to a carbonyl group.

This invention also includes all the possible isomers and mixturethereof, including diastereoisomeric mixtures and racemic mixtures,resulting from the possible combination of (R) and (S) stereochemistryat position 9 and, when substituents are present, at position 7. Thepresent invention also provides the salts of those compounds of formula1 that have salt forming groups, such as an acidic or a basic group(e.g. an amino group).

The salts are physiologically tolerable salts. In the case of compoundscontaining a basic amino group, the salts are formed with suitableinorganic or organic acids Inorganic acids are, for example,hydrochloric or sulfuric acid. Organic acids comprise mono-, di- andtricarboxylic acids, such as acetic, trifluoroacetic, tartaric andcitric acid, or sulfonic acids like, for example, methansulfonic,trifluoromethansulfonic or p-toluensulfonic acid.

Preferred compounds of formula 1 are those wherein:

R₁ is selected from:

hydrogen,

hydroxy and

methoxy;

R₂ is selected from:

hydrogen,

hydroxy and

a group of formula NR₆R₇, wherein one or both of R₆ and R₇ representhydrogen, methyl, ethyl, propyl, butyl, dimethylaminoethyl,dimethylaminopropyl, or taken together, represent 4-morpholinyl,4-methylpiperazinyl, 4-phenylpiperazinyl, 1-piperidinyl, 1-pyrrolidinyl,1,2,3,6-tetrahydropyridinyl;

R₃ is selected from:

hydrogen and

hydroxy;

R₄ is a 2-substituted thiazolyl or imidazolyl system as above defined.

Compounds of formula 1 as defined above can be prepared by

(a) reacting a compound of formula 2,

wherein R₁ and R₃ are as defined above and R₂ is hydrogen or hydroxy,with a compound of formula 3 or 7,

wherein R₆ and R₇ are as defined above, and if necessary, hydrolysingthe resultant compound and

(b) converting the resultant compound of formula 1 into a differentcompound of formula 1 by appropriate chemical reactions, such asalkylation, reduction, condensation/substitution.

In particular, the compounds of formula 1 wherein Z represents sulfurmay be obtained by reacting a compound of formula 2 with a compound offormula 3 as above defined, analogously to the procedure described inthe literature (see, for instance, The Chemistry of HeterocyclicCompounds, A. Weissberger Ed., John Wiley & Sons, 1979, vol. 34/1, p.165; or Houben-Weyl, Methoden der Organischen Chemie, vol. E 8b, GeorgThieme, 1995).

The solvent is a proper organic solvent such as methanol, ethanol,dioxane or dimethylformamide. The reaction is carried out for a periodof 1 to 24 hours at a temperature ranging from room temperature to 100°C. Preferably the solvent is a 1:1 mixture of ethanol and dioxane.

Compounds of formula 1 in which Z represents nitrogen can be prepared byreacting a compound of formula 2 with a compound of formula 7 as abovedefined, as described in the literature (see: T. L. Little and S. E.Webber J. Org. Chem. 1994, vol. 59, p. 7299).

The solvent is a proper organic solvent such as methanol, ethanol,acetonitrile, dioxane or dimethylformamide. The reaction is carried outfor a period of 1 to 24 hours at a temperature ranging from roomtemperature to 100° C. Preferably the solvent is dimethylformamide andthe reaction is carried out at room temperature. The resultingintermediate 2-acetylamino-imidazoles of formula 8

wherein R₁, R₂ and R₃ are as defined above are then hydrolized and theresultant compound of the formula 1 wherein R₆ and R₇ are hydrogens canbe converted into different compounds of the formula 1 by alkylation.According to other conversion reactions of step b), a compound offormula 1, wherein R₁, R₂, R₃ and R₄ are as defined above, can also beconverted into a different compound of formula 1 by appropriate chemicalreactions described for the anthracyclines and anthracyclinones(see: F.Arcamone, Doxorubicin Anticancer Antibiotics, Medicinal Chemistry, aseries of monographs, vol. 17, Academic Press, 1981) or by generalsynthetic procedures (see: J. March, Advanced Organic Chemistry, IV Ed.,J. Wiley & Sons, 1992). Compounds of formula 1 in which R₁, R₃ and R₄are as described above and R₂ is hydrogen are prepared by reacting thecorresponding compounds where R₂ is an hydroxyl group with a reducingagent such as sodium dithionite in a proper solvent at room temperature.Preferably, the solvent is a 1:1 mixture of water and dimethylformamide.

Compounds of formula 1 in which R₁, R₂ and R₄ are as defined above andR₂ is NR₄R₇, wherein R₆ and R₇ are as defined above, are prepared byreacting compounds of formula 1, wherein R₁, R₃ and R₄ are as definedabove and R₂ is a hydroxyl group, with an excess of ethylchloroformatein analogy to a procedure reported in the literature (see: L. Bernardiet al., Il Farmaco Ed. Sc. 1979, vol. 34, p. 884). The solvent ispreferably pyridine or methylene chloride and the reaction is carriedout at a temperature ranging from room temperature to 40° C. for aperiod of 1 to 6 hours. The resultant compound of formula 9

wherein R₁, R₃ and R₄ are as defined above, is then reacted with acompound of formula 5,

wherein R₆ and R₇ are as defined above. The solvent is a proper organicsolvent such as methanol, acetonitrile, methylene chloride,tetrahydrofuran, dimethylformamide or a mixture of them and the reactionis carried out at a temperature ranging from room temperature to 50° C.for a period of 6 to 24 hours.

A compounds of formula 1 obtained according to the procedures reportedbefore can be transformed into pharmaceutically acceptable salts thereofby dissolving the free base in a proper organic solvent likedichloromethane, methanol, ethanol or dioxane and adding a solution of apharmaceutically acceptable inorganic or organic acid in methanol,ethanol or dioxane. The resulting salt of compound 1 is obtained byevaporation or concentration of the salt solution or the salt isprecipitated by addition of diethyl ether to the salt solution.

Compounds of formula 2, wherein R₁ and R₃ are as defined above and R₂ ishydrogen or hydroxyl, are prepared starting from anthracyclinones offormula 4,

wherein R₁, R₂ and R₃ are as defined above, as described in theliterature (see: T. H. Smith et al., J. Org. Chem. 1977, vol. 42, p.3653).

Compounds of formula 4, wherein R₁, R₂ and R₃ are as defined above, maybe prepared, depending on the nature of the substituents, starting fromknown anthracyclinones by appropriate chemical modifications as reportedin the literature (see: F. Arcamone, Doxorubicin Anticancer Antibiotics,Medicinal Chemistry, a series of monographs, vol. 17, Academic Press,1981).

Compounds of formula 3 are prepared by a two step reaction in analogy toa known procedure described in the literature (see, for example, H.Hartmann and I. Reuther J. fuer Praktische Chemie 1973, vol. 315, p.144). Accordingly, by reacting a compound of formula 5 as defined above,with benzoyl isothiocianate (PhCONCS), a compound of formula 6,

wherein R₆ and R₇ are as defined above, is obtained. The solvent is aproper organic solvent such as ethanol, methanol, acetone,dimethylformamide or pyridine. The reaction is carried out for a periodof 1 to 5 hours at a temperature ranging from 0° C. to room temperature.

A compounds of formula 6 is then subjected to hydrolysis with aninorganic base, typically sodium hydroxide or potassium hydroxide, togive a desired compound 3 as defined above. The base is used in a 2- to4-fold excess with respect to compound 6. The solvent is a mixture ofwater and a proper organic solvent such as methanol, ethanol or dioxane.The reaction is carried out for a period of 1 to 24 hours and at atemperature ranging from room temperature to 100° C.

The compounds of the present invention are characterized by inhibitoryactivity on the formation of amyloid deposits by amyloidogenic proteinsand are able to induce the degradation of existing amyloid deposits.

The term amyloidoses indicates a group of diseases whose commoncharacteristic is the presence, in the extracellular space, of amyloiddeposits. Amyloidogenic proteins are proteins that have the tendency toaggregate and precipitate as amyloid. Proteins that precipitate asamyloid are both normal proteins, or truncated forms thereof, andmutated proteins, where one or more of the amino acid residues occurringat certain positions of the normal protein sequence are replaced by adifferent amino acid. Amyloid deposits are composed of insolublefibrils, also referred to as amyloid fibrils. Amyloid fibrils causecellular degeneration and organ failure that, in turn, result indifferent pathologies depending on the tissues and organs involved.

The basis for the activity of the compounds of the present invention indifferent types of amyloidosis is to be found in the commonultrastructural organization of amyloid fibrils despite the fact thatthey can be formed from a variety of widely differing proteins (see:Glenner G.G., New England J. Med. 1980, vol 302, p. 1283 and p. 1333).

The compounds of the present invention are characterized by anacceptable toxicity and can be used to make medicaments useful toprevent, to arrest or to slow down the formation of or to induce thedegradation of amyloid deposits that are formed by differentamyloidogenic proteins. Therefore, the compounds of the presentinvention can be used in the prevention and in the treatment ofdifferent types of amyloidotic diseases such as systemic amyloidoses andamyloidoses of the peripheral and central nervous system. Amyloidoses ofthe central nervous system include, for example, Alzheimer's disease,Down Syndrome, spongiform encephalopathies such as Creutzfeld-Jacobdisease and the like.

In the case of Alzheimer's disease, the protein that is found in amyloiddeposits is referred to as amyloid β-protein or β-amyloid protein and isgenerally indicated as Aβ protein. The term Aβ protein encompassesproteins of different length. In brain amyloid deposits, Aβ proteinscomposed of 39 to 43 amino acids are usually found. Neurodegenerativedisorders such as spongiform encephalopathies are characterized by theextracellular deposition of amyloid originated from a protein referredto as prion protein (PrP).

The compounds disclosed in the present invention interfere with theaggregation of monomeric Aβ1-40 peptide stimulated by a seed of Aβ1-40amyloid fibrils. The activity of the compounds was assessed according tothe procedure reported below.

An Aβ1-40 peptide monomer stock solution was prepared by dissolving thepeptide in dimethylsulfoxide at a concentration of 33.33 mg/ml. Thestock solution was further diluted 11.5 times with dimethylsulfoxide.This solution was then diluted with 10 mM phosphate buffer pH 7.4containing 150 mM sodium chloride to prepare the test solution.

To an eppendorf tube containing 47 μl of Aβ1-40 peptide monomer solutionwere added 3 μl of a 830 μM water solution of the test compoundcontaining 66.4 μM, based on the Aβ1-40 monomer content, of pre-formedsonicated Aβ1-40 fibrils: the resulting solution was 20 μM in Aβ1-40monomer, 50 μm in the test compound and contained 4 μm, based on theAβ1-40 monomer content, of pre-formed sonicated Aβ1-40 fibrils. Theaggregation was allowed to proceed for two hours at 37° C. Thesuspension was then centrifuged at 15000 rpm for 15 minutes at +4° C.,the supernatant was collected and the Aβ1-40 monomer was quantitated byHPLC.

The activity of some representative compounds is reported in Table 1.The activity is expressed as the percent of inhibition of theaggregation of a 20 μM Aβ1-40 monomer solution stimulated by 4 μm, basedon the Aβ1-40 monomer content, pre-formed sonicated Aβ1-40 fibrils.

TABLE 1 Activity of representative compounds in the seed-triggeredaggregation of AB1-40 peptide monomer. COMPOUND % INHIBITION 1d 33.7 1i31.7 1j 49.2

The compounds of the present invention can be used to make medicamentsuseful to prevent, to arrest or to slow down the formation or to inducethe degradation of amyloid deposits that are formed by differentamyloidogenic proteins. Therefore, the compounds of the presentinvention can be used in the prevention and in the treatment ofdifferent types of amyloidosis.

The present invention provides a pharmaceutical composition comprising acompound of formula 1 or a pharmaceutically acceptable salt thereof, asactive ingredient, in association with a pharmaceutically acceptablecarrier, excipient or other additive, if necessary. Also provided is acompound of formula 1, as defined above, or a pharmaceuticallyacceptable salt thereof, for use in the treatment of the human or animalbody. Further, the present invention provides the use of a compound offormula 1, or a pharmaceutically acceptable salt thereof, in themanufacture of a medicament for use in the treatment of an amyloidosisdisease.

The pharmaceutical composition containing a compound of formula 1 orsalts thereof may be prepared in a conventional way by employingconventional non-toxic pharmaceutical carriers or diluents in a varietyof dosage forms and ways of administration.

In particular, the compounds of formula 1 can be administered:

A) orally, for example, as tablets, troches, lozenges, aqueous or oilysuspension, dispersible powders or granules, emulsions, hard or softcapsules, or syrups or elixirs. Compositions intended for oral use maybe prepared according to any method known in the art for the manifactureof pharmaceutical compositions and such composition may contain one ormore agents selected from the group consisting of sweetening agents,flavouring agents, coloring and preserving agents in order to provideelegant and palatable preparations.

Tablets contain the active ingredient in admixture with non-toxicpharmaceutically acceptable eccipients which are suitable for themanifacture of tablets. These excipient may be, for example, inertdiluents, such as calcium carbonate, sodium carbonate, lactose, calciumphosphate or sodium phosphate; granulating and disintegrating agents,for example maize starch or alginic acid; binding agents, for examplemaize starch, gelatin or acacia, and lubrificating agents, for examplemagnesium stearate or stearic acid or talc. The tablets may be uncoatedor they may be coated by known techniques to delay disintegration andabsorption in the gastrointestinal tract and thereby provide a sustainedaction over a longer period. For example, a time delay material suchglyceryl monostearate or glyceryl distearate may be employed.

Formulations for oral use may also be presented as hard gelatin capsuleswherein the active ingredient is mixed with an inert solid diluent, forexample calcium carbonate, calcium phosphate or kaolin, or soft gelatincapsules wherein the active ingredient is mixed with water or an oilmedium, for example peanut oil, liquid paraffin or olive oil. Aqueoussuspensions contain the active materials in admixture with excipientssuitable for the manifacture of aqueous suspensions. Such excipients aresuspending agents, for example sodium carboxymethylcellulose,methylcellulose, hydroxypropylmethyl cellulose, sodium alginate,polyvinylpyrrolidone, gum tragacanth and gum acacia; dispersing orwetting agents may be naturally-occurring phosphatides, for examplelecithin, or condensation products of an alkylene oxide with fattyacids, for example polyoxyethylene stearate, or condensation products ofethylene oxide with long chain aliphatic alcohols, for exampleheptadecaethyleneoxyacetamol, or condensation products of ethylene oxidewith partial esters derived from fatty acids and an hexitol such aspolyoxyethylene sorbitol monooleate, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol anhydrides, for example polyoxysorbitan monooleate. The saidaqueous suspension may also contain one or more preservatives, forexample ethyl or n-propyl p-hydroxybenzoate, one or more coloringagents, one or more flavouring agents, one or more sweetening agentssuch as sucrose or saccharin.

Oily suspension may be formulated by suspending the active ingredient ina vegetable oil, for example arachis oil, olive oil, seseme oil, coconutoil or in a mineral oil such as liquid paraffin. The oily suspension maycontain a thickening agent, for example beewax, hard paraffin or cetylalcohol. Sweetening agents, such as those set forth above, and flavoringagents may be added to provide a palatable oral preparation.

These compositions may be preserved by the addition of an antioxidantsuch as ascorbic acid. Dispersible powders and granules suitable forpreparation of an aqueous suspension by the addition of water providethe active ingredient in admixture with a dispersing or wetting agent, asuspending agent and one or more preservatives. Suitable dispersing orwetting agents and suspending agents are exemplified by those alreadymentioned above. Additional excipients, for example sweetening,flavouring and coloring agents may also be present.

The pharmaceutical compositions of the invention may also be in the formof oil-in-water emulsions.

The oily phase may be a vegetable oil, for example olive oil or arachisoil, or a mineral oil, for example liquid paraffin or mixtures of these.

Suitable emulsifying agents may be naturally-occurring gums, for examplegum acacia or gum tragacanth, naturally-occurring phosphatides, forexample soy bean, lecithin, and esters or partial esters derived fromfatty acids and hexitol anhydrides, for example sorbitan monooleate, andcondensation products of the said partial esters with ethylene oxide,for example polyoxyethylene sorbitan monooleate. The emulsions may alsocontain sweetening and flavoring agents. Syrups and elixirs may beformulated with sweetening agents, for example glycerol, sorbitol orsucrose. Such formulations may also contain a demulcent, a preservative,coloring and flavoring agents.

B) Parenterally, either subcutaneously or intravenously orintramuscularly, or intrasternally, or by infusion techniques. Thepharmaceutical compositions may be in the form of a sterile injectableaqueous or olagenous suspensions.

This suspensions may be formulated according to the known art usingthose suitable dispersing or wetting agents and suspending agents whichhave been mentioned above. The sterile injectable preparation may alsobe a sterile injectable solution or suspension in a non-toxicparenterally-acceptable diluent or solvent, for example a solution in1,3-butanediol. Among the acceptable vehicles and solvents that may beemployed are water, Ringer's solution and isotonic sodium chloridesolution. In addition, sterile fixed oils are conventionally employed asa solvent or suspending medium.

For this purpose any bland fixed oils may be conventionally employedincluding synthetic mono or diglycerides. In addition fatty acids suchas oleic acid find use in the preparation of injectables.

The present invention further provides a method of treating a human oranimal, e.g. a mammal, suffering from or susceptible to an amyloidoticdisease, which method comprises administering thereto a non-toxic andtherapeutically effective amount of a compound of the formula 1 or apharmaceutically acceptable salt thereof.

A typically daily dose is from about 0.1 to about 50 mg per 30 Kg ofbody weight, according to the activity of the specific compound, theage, weight and conditions of the subject to be treated, the type andthe severity of the disease, and the frequency and route ofadministration; preferably, daily dosage levels are in the range of 5 mgto 2 g. The amount of active ingredient that may be combined with thecarrier materials to produce a single dosage form will vary dependingupon the host treated and the particular mode of administration. Forexample, a formulation intended for oral may contain from 5 to about 95%of the total composition. Dosage unit forms will generally containbetween from about 5 mg to about 500 mg of the active ingredient.

The following examples illustrate the invention without limiting it.

EXAMPLE 1 9-Deacetyl-9-(2-aminothiazol-4-yl)-daunomycinone (1a)

0.5 g (1.05 mmol) of 14-bromodaunomycinone 2 (R₁═OCH₃; R₂═R₃═OH) wassuspended in 100 ml of a 1:1 mixture (by volume) of ethanol and dioxaneand 76 mg (1.26 mmol) of thiourea were added. The reaction was kept atroom temperature for 6 hours. The solvent was then removed under reducedpressure, the residue was dissolved in methylene chloride and washedwith a diluted solution of ammonium hydrate and then with water. Theorganic phase was dried over anhydrous sodium sulphate, thenconcentrated and crystallized from ethylacetate to afford 0.31 g (60%yield of the title compound.

FAB-MS, m/z: 455 [M+H]⁺; 437 [M+H-H₂O]⁺; 421 [M+H-2H₂O]⁺; ¹H-NMR (200MHz, DMSO-d₆) δ: 2.20 (m, 2H, CH ₂-8); 3.10 (m, 2H, CH ₂-10); 3.97 (s,3H, OCH ₃); 5.03 (m, 1H, H-7); 5.30 (d, J=7.7 Hz, 1H, OH-7); 5.78 (S,1H, OH-9); 6.44 (s, 1H, thiazole proton); 6.89 (broad signal, 2H, NH ₂);7.62 (m, 1H, H-3); 7.88 (m, 2H, H-1 +H-2); 13.24 (broad signal, 1H,OH-11); 13.96 (broad signal, 1H, OH-6).

The compound was then converted into the corresponding hydrochloride bytreatment with methanol saturated with gaseous hydrogen chloride andthen crystallized from acetone (m.p.>270° C.

EXAMPLE 2 9-Deacetyl-9-(2-ethylamino-thiazol-4-yl)-daunomycinone (1b)

Operating as in example 1, but employing N-ethylthiourea (prepared asdescribed in the literature; m.p. 101-103° C.) instead of thiourea, thetitle compound was obtained in 93% yield.

ESI-MS, m/z: 483 [M+H]⁺; 465 [M+H-H₂O]⁺; 447 [M+H-H₂O]⁺. ¹H-NMR (200MHz,DMSO-d₆) δ: 1.12 (t, J=7.1 Hz, 3H, CH₂CH ₃); 2.21 (m, 2H, CH ₂-8); 3.13(s, 2H, CH ₂-10); 3.16 (m, 2H, CH ₂CH₃); 3.98 (s, 3H, OCH ₃); 5.04 (m,1H, H-7); 5.32 (d, J=7.6 Hz, 1H, OH-7); 5.81 (s, 1H, OH-9); 6.48 (s, 1H,thiazole proton); 7.49 (t, J=5.6 Hz, 1H, NHCH₂); 7.63 (m, 1H, H-3); 7.89(m, 2H, H-1+H-2); 13.26 (broad signal, 1H, OH-11); 13.98 (broad signal,1H, OH-6).

Compound 1b was then converted into the corresponding hydrochloride, asdescribed in example 1 (m.p. 242-244° C.).

EXAMPLE 3 9-Deacetyl-9-(2-diethylamino-thiazol-4-yl)-daunomycinone (1c)

Operating as in example 1, but employing N,N diethylthiourea (preparedas described in the literature; m.p. 99-101° C.), the title compound wasobtained in 83% yield.

ESI-MS, m/z: 511 [M+H]⁺; 493 [M+H-H₂O]⁺; 475 [M+H-2H₂O]⁺. ¹H-NMR (400MHz, DMSO-d₆) δ: 1.12 (t, J=7.3 Hz, 6H, CH₂CH ₃); 2.16 (d, J=14.1 Hz,1H, H-8eq); 2.26 (dd, J=4.7, 14.1 Hz, 1H, H-8ax); 3.12 (m, 2H, CH ₂-10);3.39 (q, J=7.3 Hz, 4H, CH ₂CH₃); 3.97 (s, 3H, OCH ₃); 5.01 (m, 1H, H-7);5.29 (d, J=7.7 Hz, 1H, OH-7); 5.79 (s, 1H, OH-9); 6.54 (s, 1H, H-3);7.86 (m, 2H, H-1+H-2); 13.20 (broad signal, 1H, OH-11); 13.95 (broadsignal, 1H, OH-6).

Compound 1c was then converted into the corresponding hydrochloride asdescribed in example 1 (m.p.>270° C.).

EXAMPLE 4 9-Deacetyl-9-[2-(2-dimethylaminoethylamino)-thiazol-4-yl]-daunomycinone (1d)

Operating as in example 1, but employingN-(2,2-dimethylaminoethyl)-thiourea (prepared as described in theliterature; m.p. 71-73° C.), the title compound was obtained in 76%yield.

ESI-MS, m/z: 526 [M+H]⁺; 508 [M+H-H₂O]⁺; 490 [M+H-2H₂O]⁺. ¹H-NMR (400MHz, DMSO-d₆) δ: 2.13 (s, 6H, N(CH ₃)₂); 2.20 (m, 2H, CH ₂-8); 2.38 (t,J=6.8 Hz, 2H, CH ₂N(CH₃)₂); 3.11 (s, 2H, CH ₂-10); 3.25 (m, 2H, NHCH ₂);3.97 (s, 3H, OCH ₃); 5.02 (m, 1H, H-7); 5.30 (d, J=7.7 Hz, 1H, OH-7);5.78 (s, 1H, thiazole proton); 7.40 (t, J=5.5 Hz, 1H, NHCH₂); 7.61 (m,1H, H-3); 7.86 (m, 1H, H-1+H-2); 13.20 (broad signal, 1H, OH-11); 13.95(broad signal, 1H, OH-6).

Compound id was then converted into the corresponding dihydrochloride asdescribed in example 1 (m.p. 270-272° C.).

EXAMPLE 5 9-Deacetyl-9-[2-(3-dimethylaminopropylamino)-thiazol-4-yl]-daunomycinone (1e)

Operating as described in example 1, but employingN-(3,3-dimethylaminopropyl)-thiourea (prepared as described in theliterature; m.p. 64-66° C.), the title compound was obtained in 60%yield.

FAB-MS, m/z: 540 [M+H]⁺; 522 [M+H-H₂O]⁺; 504 [M+H-2H₂O]⁺. ¹R-NMR (200MHz, DMSO-d₆) δ: 1.64 (m, 2H, NHCH₂CH ₂CH₂NMe₂); 2.08 (s, 6H, N(CH ₃)₂);2.23 (m, 4H, CH ₂-8+CH ₂NMe₂); 3.11 (s, 2H, CH ₂-10); 3.15 (m, 2H, NHCH₂); 3.97 (s, 3H, OCH ₃); 5.02 (m, 1H, H-7); 5.30 (broad signal, 1H,OH-7); 5.77 (s, 1H, OH-9); 6.47 (s, 1H, thiazole proton); 7.49 (t, J=5.5Hz, 1H, NHCH₂); 7.61 (m, 1H, H-3); 7.86 (m, 2H, H-1+H-2); 13.30, 13.80(two broad signals, 2H, OH-11+OH-6).

Compound 1e was then converted into the corresponding dihydrochloride asdescribed in example 1 (m.p. 229-231° C.).

EXAMPLE 6 9-Deacetyl-9-[2-(morpholin-4-yl)-thiazol-4-yl]-daunomycinone(1f)

Operating as in example 1, but employing 4-thiocarbamoyl-morpholine(prepared as described in the literature; m.p. 177-179° C.), the titlecompound was obtained in 75% yield.

ESI-MS, m/z: 525 [M+H]⁺; 507 [M+H-H₂O]⁺; 489 [M+H-2H₂O]⁺. ¹H-NMR (200MHz, DMSO-d₆) δ: 2.20 (m, 2H, CH ₂₋₈); 3.12 (s, 2H, CH ₂₋₁₀); 3.34 (m,4H, CH ₂NHC₂); 3.69 (m, 4H, CH ₂OCH ₂); 3.97 (S. 3H, OCH ₃); 5.02 (m,1H, H-7); 5.33 (d, J=7.6 Hz, 1H, OH-7); 5.87 (s, 1H, OH-9); 6.74 (s, 1H,thiazole proton); 7.62 (m, 1H, H-3); 7.86 (m, 2H, H-1+H-2); 13.24 (s,1H, OH-11); 13.95 (s, 1H, OH-6).

Compound 1f was then converted into the corresponding hydrochloride asdescribed in example 1 (m.p.>270° C.).

EXAMPLE 7 9-Deacetyl-9-[2-(morpholin-4-yl)-thiazol-4-yl]-daunomycinone(1g)

Operating as in example 1, but employing1-thiocarbamoyl-4-phenylpiperazine (prepared as described in theliterature; m.p. 195-197° C.), the title compound was obtained in 52%yield (m.p. 135-137° C.).

ESI-MS, m/z: 600 [M+H]⁺; 582 [M+H-H₂O]⁺; 564 [M+H-2H₂O]⁺. ¹H-NMR (200MHz, DMSO-d₆) δ: 2.22 (m, 2H, CH ₂-8); 3.16 (s, 2H, CH ₂-10); 3.24, 3.51(two multiplets, 8H, piperazine methylenes); 3.99 (s, 3H, OCH ₃); 5.08(m, 1H, H-7); 5.35 (d, J=7.8 Hz, OH-7); 5.89 (s, 1H, OH-9); 6.75 (s, 1H,thiazole proton); 6.80 (m, 1H, phenyl para-H); 6.99 (m, 2H, phenylortho-H); 7.22 (m, 2H, phenyl meta-H); 7.65 (m, 1H, H-3); 7.92 (m, 2H,H-1+H-2); 13.29 (s, 1H, OH-11); 14.00 (s, 1H, OH-6).

EXAMPLE 89-Deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1h)

Operating as in example 1, but employing1-thiocarbamoyl-4-methylpiperazine (prepared as described in theliterature; m.p. 207-209° C.), the title compound was obtained in 45%yield (m.p. 145-151° C.).

ESI-MS, m/z: 538 [M+H]⁺; 520 [M+H-H₂O]⁺; 502 [M+H-2H₂O]⁺. 1H-NMR (400MHz, DMSO-d₆) δ: 2.20 (m, 2H, CH ₂-8); 2.20 (s, 3H, NCH ₃); 2.40 (m, 4H,Me—N(CH ₂)₂); 3.10 (s, 2H, CH ₂-10); 3.36 (m, 4H, thiazole-N(CH ₂)₂);3.95 (s, 3H, OCH ₃); 4.99 (m, 1H, H-7); 5.29 (d, J=7.7 Hz, 1H, OH-7);5.81 (S, 1H, OH-9); 6.70 (s, 1H, thiazole proton); 7.56 (m, 1H, H-3);7.82 (m, 1H, H-1 +H-2); 13.20 (s, 1H, OH-11); 13.90 (s, 1H, OH-6).

EXAMPLE 97-Deoxy-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1I)

Compound 1h (0.5 g, 0.93 mmol) was dissolved in 15 ml ofdimethylformamide under nitrogen and sodium dithionite hydrate (0.71 g,3.7 mmol ) dissolved in 15 ml of water was added. The reaction was keptat room temperature for 48 hours. The solvent was then removed underreduced pressure; the residue was redissolved in methylene chloride andwashed with a diluted solution of ammonium hydrate and then with water.The organic layer was dried on anhydrous sodium sulphate, thenconcentrated and crystallized from diethyl ether to give 0.39 g (81%yield) of the title compound.

ESI-MS, m/z: 522 [M+H]⁺; 504 [M+H-H₂O ⁺. ¹H-NMR (200 MHz, CDCl₃) δ: 2.17(m, 2H, CH2-8); 2.35 (s, 3H, NCH ₃); 2.53 (m, 4H, Me-N(CH ₂)₂); 3.00 (m,2H, CH2-7); 3.19 (s, 2H; CH ₂-10); 3.51 (m, 4H, thiazole-N(CH ₂)₂); 4.08(s, 3H, OCH ₃); 6.35 (s, 1H, thiazole proton); 7.36 (dd, J=1.2, 8.5 Hz,1H, H-3); 7.75 (dd, J=7.8, 8.5 Hz, 1H, H-2); 8.04 (dd, J=1.2, 7.8 Hz,1H, H-1); 13.53 (s, 1H, OH-11); 13.89 (s, 1H, OH-6).

Compound 1i was then converted into the corresponding dihydrochloride asdescribed in example 1 (m.p. 227-229° C.).

EXAMPLE 107-Deoxy-7-(4-morpholinyl)-9-deacetyl-9-[2-(4-methyl-perazin-1-yl)-thiazol-4-yl]-daunomycinone(1j)

Compound 1h (0.5 g, 0.93 mmol) and triethylamine (1.1 ml, 7.44 mmol)were dissolved in 20 ml of methylene chloride and ethylchloroformate(0.75 ml, 7.44 mmol) in methylene chloride was added. After 5 hours atroom temperature the mixture was washed with water, the organic layerdried over anhydrous sodium sulphate and then evaporated to dryness.Without further purification the corresponding tricarbonate 8 (R₁═OCH₃,R₃═OH; R₄═2-(4-methyl-piperazin-1-yl)-thiazol-4-yl) was redissolved inmethylene chloride and morpholine (0.81 ml, 9.3 mmol) was added. After48 hours under stirring at room temperature the mixture was washed withwater, the organic layer dried over anhydrous sodium sulphate andevaporated to obtain a residue which was chromatographed on silica gel(eluant: cyclohexane/acetone 9:1) to give 0.11 g (20% yield) of thetitle compound.

ESI-MS, m/z: 607 (M+H]⁺; 520 [M+H-morpholine]⁺; 502[M+H-morpholine-H₂O]⁺. ¹H-NMR (200 MHz, CDCl₃) δ: 2.20 (dd, J=3.4, 14.4Hz, 1H, H-8ax); 2.33 (s, 3H, NCH ₃); 2.35 (m, 1H, H-8eq); 2.49 (m, 4H,Me—N(CH ₂)₂); 2.50, 3.03 (2 m, 4H, morpholine N(CH ₂)₂); 3.34 (d, J=20.2Hz, 1H, H-10eq); 3.45 (d, J=20.2 Hz, 1H, H-10ax); 3.46 (m, 4H,thiazole-N(CH ₂)₂); 3.66 (m, 4H, morpholine O(CH ₂)₂); 4.10 (s, 3H, OCH₃); 4.35 (m, 1H, H-7); 6.69 (s, 1H, thiazole proton); 7.39 (dd, J=1.0,8.5 Hz, 1H, H-3); 7.78 (dd, J=7.8, 8.5 Hz, 1H, H-2); 8.04 (dd, J=1.0,7.8 Hz, 1H, H-1); 8.50 (broad signal, 1H, OH-9); 13.35 (s, 1H, OH-11);14.19 (s, 1H, OH-6).

Compound 1j was then converted into the corresponding trihydrochlorideas described in example 1 (m.p. 180-182° C.).

Operating as described in example 1, the following compounds may also beprepared.

EXAMPLE 11 9-Deacetyl-9-[2-(piperidin-1-yl)-thiazol-4-yl]-daunomycinone(1k) EXAMPLE 129-Deacetyl-9-[2-(1,2,3,6-tetrahydropyridin-1-yl)-thiazol-4-yl]-daunomycinone(1k) EXAMPLE 139-Deacetyl-9-[2-(pyrrolidin-1-yl)-thiazol-4-yl]-daunomycinone (1l)

Operating as described in example 10, the following compounds may alsobe prepared.

EXAMPLE 147-Deoxy-7-ethylamino-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1m) EXAMPLE 157-Deoxy-7-diethylamino-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1n) EXAMPLE 16 7-Deoxy-7-(3,3-dimethylaminopropylamino)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1o) EXAMPLE 177-Deoxy-7-(pyrrolidin-1-yl)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1p) EXAMPLE 187-Deoxy-7-(piperidin-1-yl)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1g) EXAMPLE 197-Deoxy-7-(1,2,3,6-tetrahydro-pyridin-1-yl)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)thiazol-4-yl]-daunomycinone(1r) EXAMPLE 207-Deoxy-7-(4-methyl-piperazin-1-yl)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone(1s) EXAMPLE 21

Tablets containing the following ingredients may be produced in aconventional manner:

Ingredient Per Tablet Compound 1 25.0 mg Lactose 125.0 mg  Maize starch75.0 mg Talc  4.0 mg Magnesium stearate  1.0 mg

Total weight 230.0 mg

EXAMPLE 22

Capsules containing the following ingredients may be produced in aconventional manner:

Ingredient Per capsule Compound 1 50.0 mg Lactose 165.0 mg  Maize starch20.0 mg Talc  5.0 mg Capsule weight 240.0 mg 

What is claimed is:
 1. A compound of formula 1

wherein: R₁ is selected from: hydrogen, hydroxy, a group of formula OR₅wherein R₅ is C₁-C₆ alkyl, C₂-C₆ alkenyl or C₃-C₈ cycloalkyl, halogenand amino which may be unsubstituted or mono or disubstituted by C₁-C₆alkyl, C₂-C₆ alkenyl, aralkyl, acyl or trifluoroacetyl; R₂ is selectedfrom: hydrogen, hydroxy and a group NR₆R₇ wherein R₆ and R₇independently represent hydrogen, an optionally substituted C₁-C₆ alkyl,C₂-C₆ alkenyl, C₃-C₈ cycloalkyl or, taken together with the nitrogenatom, represent an optionally substituted C₃-C₈ heterocyclic ring; R₃ isselected from: hydrogen and hydroxy; R₄ is an heterocycle of formula A:

wherein Z represents sulfur or nitrogen and R₆ and R₇ are as definedabove and the pharmaceutically acceptable salt thereof.
 2. A compoundaccording to claim 1, wherein R₁ is selected from the group consistingof hydrogen, hydroxy and methoxy; R₂ is selected from the groupconsisting of hydrogen, hydroxy and a group of formula NR₆R₇, whereinone or both of R₆ and R₇ represent hydrogen, methyl, ethyl, propyl,butyl, dimethylaminoethyl, dimethylaminopropyl, or taken togetherrepresent 4-morpholinyl, 4methylpiperazinyl, 4-phenylpiperazinyl,1-piperidinyl, 1-pyrrolidinyl, or 1,2,3,6-tetrahydropyridinyl; R₃ isselected from the group consisting of hydrogen and hydroxy; R₄ is a2-substituted thiazolyl or imidazolyl system as defined in claim 1, orthe pharmaceutically acceptable salt thereof.
 3. A compound according toclaim 1, which is7-deoxy-7-(4-morpholinyl)-9-deacetyl-9-[2-(4-methyl-piperazin-1-yl)-thiazol-4-yl]-daunomycinone,or a pharmaceutically acceptable salt thereof.
 4. A process forpreparing a compound of formula 1 as defined in claim 1, comprising: (a)reacting a compound of formula 2,

wherein R₁ and R₃ are as defined in claim 1 and R₂ is hydrogen orhydroxy, with a compound of formula 3 or 7,

wherein R₆ and R₇ are as defined in claim 1; and  optionally hydrolyzingthe resultant compound; and (b) reacting the resultant compound offormula 1 by alkylation, reduction, condensation or substitution, and/oroptionally converting the resultant compound into a pharmaceuticallyacceptable salt.
 5. A process according to claim 4 for preparing acompound of formula 1 wherein Z is sulfur, wherein in step (a) acompound of formula 2 is reacted with a compound of formula 3 in anorganic solvent for a period of 1 to 24 hours at a temperature rangingfrom room temperature to 100° C.
 6. A process according to claim 4 forpreparing a compound of formula 1 wherein Z is nitrogen, wherein in step(a) a compound of formula 2 is reacted with a compound of formula 7 inan organic solvent for a period of 1 to 24 hours at a temperatureranging from room temperature to 100° C., and the resulting intermediate2-acetylamino-imidazole of formula 8

wherein: R₁ is selected from the group consisting of hydrogen, hydroxy,a group of formula OR₅ wherein R₅ is C₁-C₆ allyl, C₂-C₆ alkenyl or C₃-C₈cycloalkyl, halogen and amino which may be unsubstituted or mono ordisubstituted by C₁-C₆ alkyl, C₂-C₆ alkenyl, aralkyl, acyl ortrifluoroacetyl; R₂ is selected from the group consisting of hydrogen,hydroxy and a group NR₆R₇ wherein R₆ and R₇ independently representhydrogen, an optionally substituted C₁-C₆ alky, C₂-C₆ alkenyl, C₃-C₈cycloalkyl or, taken together with the nitrogen atom, represent anoptionally substituted C₃-C₈ heterocyclic ring; R₃ is selected from thegroup consisting of hydrogen and hydroxy; is then hydrolized.
 7. Apharmaceutical composition which comprises, as active ingredient, acompound of formula 1 as defined in claim 1, or a pharmaceuticallyacceptable salt thereof, in admixture with a pharmaceutically acceptablecarrier or diluent.
 8. A method, comprising: administering a non-toxicand effective amount of the compound of formula (I), as defined in claim1, or a pharmaceutically acceptable salt thereof to a subject in needthereof, thereby slowing the formation of an amyloid deposit ordegrading an amyloid deposit.
 9. A method of treating Alzheimer'sdisease, spongiform encephalopathies or Down's syndrome, comprising:administering to a subject in need thereof an effective amount of thecompound of formula (I), as defined in claim 1, or a pharmaceuticallyacceptable salt thereof.